The beginning of winter heralds the beginning of respiratory infections of different kinds. Besides being troublesome, the infections tend to spread from one person to another. None other than William Shakespeare described better the need to control infection when he wrote:

Pursue him to his house and pluck him thence,

Lest his infection being of catching nature,

Spread further (Coriolanus)

Upper respiratory tract infections, grouped together as upper respiratory catarrh (URC) or common cold, are common during the change of seasons. Literally speaking, common cold is only one of the several different infections of the upper respiratory tract which consist of those of the nose, mouth, throat and their contents such as the tonsils, pharynx and larynx. These organs are generally involved together although individual affliction may also occur. Infectious conditions such as rhinitis, tonsillitis, pharyngitis, laryngitis or tracheitis can constitute one or different forms of a URC — "itis" denotes the inflammation of tissues in medical terminology.

The acute onset of symptoms of cough, the running nose, sore throat and/or throat clearing, fever, general prostration, weakness and fatigue indicate the presence of a viral URC. It is mostly self-limiting and only symptomatic treatment suffices. Bacterial infections and the presence of purulent secretions require the use of antibiotics. The decision should be made by the doctor since an inappropriate use of drugs, especially the antibiotics, can cause more problems without doing any good.

These are the lower respiratory tract infections i.e. bronchitis and pneumonias, which require more urgent attention. Not infrequently, the upper respiratory infection may spread and extend downwards to involve the lower respiratory tract. This may, however, happen only if the infection is severe to start with or the person who is infected is immunosuppressed (weak in his defense against the microorganisms). Both bronchitis and pneumonia frequently involve the otherwise healthy individuals.

Bronchitis may occur in an individual following a sudden exposure to cold, smoke or other inhalational chemicals and fumes. It may also complicate the otherwise stable course of a patient with chronic bronchitis or bronchial asthma. Patients with chronic respiratory diseases in particular need to be careful due the arrival of winter.

Besides the change in temperature, the winter season is notoriously dangerous because of air-pollution. The dust and smoke particles in the air condense and combine; the hydrocarbon present in the air from vehicular and industrial exhausts get oxidized dur to the sunlight. The combination of smoke and the winter fog gets the nomenclature "smog" — a real danger. Several episodes of smog in the late nineties and early fifties in Europe and the USA were labeled as "epidemics" because of their widespread nature. Smog is dangerous by itself but much more so by predisposing one to respiratory infections.

Pneumonia is the real prototype of lung infection. It represents the inflammation of the lung cells or pneumocytes and should, therefore, be called pneumonitis. Pneumonias are classified variously depending on the cause (infectious, chemical or toxic), the setting (e.g. community or hospital-acquired), the host (immunosuppressed) and the agent (pneumococcal, klebsiella, fungal, viral etc.).

Tobacco smoking is the other major cause of bronchitis. Chronic bronchitis is almost always associated with smoking. Acute bronchitis, on the other hand, results from acute, heavy exposures to dust and smoke. In children, passive smoking on exposure to smoke from parents is an important factor for predisposition to respiratory infection.

The clinical picture of pneumonia is known since 4th to 5th century BC when Hippocrates vividly described..... "when pneumonia is at its height.....It is bad if he had dyspnoea.... and if sweat comes out about the neck and head, for such sweats are bad, as proceeding from the suffocation, rales and the violence of the disease". Typically, there is fever and cough which may be accompanied with chest pain, rigors, chills and sweating. Sputum production is nil or insignificant but may increase with time if complications occur. It should be clearly remembered that pneumonia can go on to develop pus formation in the lungs, the pleural cavity and even elsewhere in the body.

An individual needs to be careful to prevent the occurrence of respiratory infection. The avoidance of exposure to cold is important. Warm clothing should be used for outdoor activities. Early morning walks should preferably be avoided especially by people with pre-existing lung and/or other systemic diseases.

Similarly, it is important to stay away from dust and smoke as much as possible. General civic rules should be practiced and coughing, spitting and nose blowing should not be done in the presence of others. Infection is not easy to prevent. When it does occur, early medical advice may help prevent further problems. A trouble is better nipped in the bud than allowed to grow.